The present invention relates to a process for manufacturing a vehicle body with a roof unit containing an outer skin and an inward facing ceiling, or an outer skin and an inward facing ceiling with a ceiling frame, whereby the roof unit is in the form of a unit ready for installation and, a basic structure, and the ceiling and the outer skin along with the basic structure feature configurations for joining that mate with each other at their mutual places for joining, this for a body of a road-bound vehicle fitted together horizontally, and particular roof units.